Is Collum Femoris Preserving Stem (CFP) an Epiphyseal-Stabilized Prosthesis? A Long-Term Single-Center Series Follow Up of 705 Cases.

Abstract

Background: The global increase in total hip arthroplasty (THA) has led to widespread use of cementless femoral stems. The Collum Femoris Preserving (CFP) stem, initially designed as an epiphyseal-stabilized prosthesis, aims to preserve proximal bone and reduce stress shielding. However, long-term observations have revealed unexpected proximal bone resorption and distal sclerosis, challenging this classification. This study aims to reassess the fixation pattern and long-term complications of CFP stems to inform clinical decision-making.

Methods: Between 2006 and 2012, 497 patients (705 hips) were included. The primary outcomes included prosthesis survival, periprosthetic bone remodeling, and clinical outcomes, assessed using the Harris Hip Score (HHS). Kaplan-Meier survival analysis was performed, with endpoints of prosthesis loosening and reoperation. Radiographic data were analyzed to evaluate periprosthetic bone remodeling.

Results: A total of 497 patients (705 hips) with a mean follow-up of 10.4 years were included. The long-term survival rate of the CFP stem was 95.32%, with a 97.2% survival rate for aseptic loosening and 95.5% for reoperation. Complications included 2.84% aseptic loosening, 0.99% infection, 0.99% periprosthetic fractures, 0.57% dislocation, and 1.42% heterotopic ossification. The CFP stem, which has not shown signs of aseptic loosening, exhibits radiographic features characteristic of a distal-stabilized prosthesis.

Conclusion: The long-term survival rate of the CFP prosthesis was 95.32%. Radiographic findings indicate that the CFP prosthesis should be considered a distal-stabilized prosthesis rather than the traditionally regarded epiphyseal-stabilized prosthesis.